Partial support is requested for the 13th Gordon Research Conference on Chronobiology, to be held in II Ciocco, Barga, Italy. In recent years, the significance of internal body clocks (circadian clocks) for the regulation and adjustment of temporal physiology has become increasingly clear and, as a consequence, much effort has been devoted to the analysis of the mechanisms underlying circadian processes. Recognition of the key role played by circadian rhythms in human health and disease and a recent series of landmark discoveries regarding the molecular mechanisms that both generate and regulate the circadian system has led to a remarkable expansion of the field. Today, chronobiological research attracts a host of researchers from a broad range of disciplines, including molecular genetics, photobiology, sleep medicine, psychiatry, and gerontology. The aims of the Gordon Conference on Chronobiology are: (1) To provide a forum for discussion and for seeking general principles in the rapidly expanding field of chronobiology. (2) To stimulate interactions among researchers working in the various sub-disciplines of chronobiology and thus to enhance the coherence of the research field as a whole. (3) To intensify interactions between young and established researchers and thus sustain high-quality chronobiological research. (4) To promote both national and international collaboration by bringing together scientists from many different groups and countries. (5) To promote translational research by bringing together researchers employing model organisms with researchers using human subjects for circadian research. The conference will achieve these goals by assembling approximately 130 scientists who will encompass individuals from different countries, age groups, genders, and using different research models. We are encouraging the active participation of minority groups by contacting minority colleges directly (e.g., Morehouse). The program will focus on new developments in key research areas (see Tentative Program). In accordance with the highly successful Gordon Conference format, a restricted number of lectures will be presented in 9 morning and evening sessions with ample time for discussions. Three late-afternoon poster sessions will allow participants to present additional data.